Fluoroelastomer composition

ABSTRACT

A fluoroelastomer composition comprising (1) a fluoroelastomer consisting essentially of tetrafluoroethylene units, perfluoro(alkyl vinyl ether) units and cyano group containing perfluorovinyl ether units; (2) a specified silane coupling agent; (3) a crosslinking agent and (4) an inorganic filler. This fluoroelastomer composition enables improving the moldability of a crosslinkable composition containing an inorganic filler other than carbon black.

FIELD OF THE INVENTION

[0001] The present invention relates to a fluoroelastomer composition.More particularly, the present invention relates to a crosslinkablecomposition comprising a fluoroelastomer having a cyano group as acrosslinkable group, a crosslinking agent, an inorganic filler and anorganosilicon compound.

BACKGROUND OF THE INVENTION

[0002] Japanese Patent Laid-open Publication No. 8(1996)-120144describes a fluoroelastomer composition comprising a terpolymer oftetrafluoroethylene, a perfluoro(alkyl vinyl ether) and a cyano groupcontaining perfluorovinyl ether represented by the general formula:

CF₂═CFO(CF₂)_(n)OCF(CF₃)CN   (n: 2-5)

[0003] and, as a crosslinking agent, a bis(aminophenyl) compoundrepresented by the general formula:

[0004] wherein A represents an alkylidene group having 1 to 6 carbonatoms or a perfluoroalkylidene group having 1 to 10 carbon atoms, andeach of X and Y represents a hydroxyl group or an amino group.

[0005] Japanese Patent Laid-open Publication No. 9(1997)-31284 describesa fluoroelastomer composition comprising a terpolymer oftetrafluoroethylene, a perfluoro(alkyl vinyl ether) and a cyano groupcontaining perfluorovinyl ether and, as a crosslinking agent, abisamidoxime compound represented by the general formula:

[0006] wherein n is an integer of 1 to 10.

[0007] These crosslinkable compositions are preferably filled withcarbon black, whereby a molding with enhanced mechanical properties canbe provided. Although the crosslinkable compositions can be filled withinorganic fillers other than carbon black, it occurs that, with respectto moldability, less desirable results than in the filling of carbonblack can be attained thereby.

OBJECT OF THE INVENTION

[0008] The present invention is intended to solve the above problem, andan object of the present invention is to attain striking improvement ofthe moldability of a crosslinkable composition comprising a terpolymerof tetrafluoroethylene, a perfluoro(alkyl vinyl ether) and a cyano groupcontaining perfluorovinyl ether, a crosslinking agent and an inorganicfiller other than carbon black.

SUMMARY OF THE INVENTION

[0009] According to the present invention, for solving the aboveproblem, there is provided a fluoroelastomer composition comprising:

[0010] 1) a fluoroelastomer consisting essentially oftetrafluoroethylene units, perfluoro(alkyl vinyl ether) units and cyanogroup containing perfluorovinyl ether units, provided that the alkyl ofthe perfluoro(alkyl vinyl ether) has 1 to 5 carbon atoms;

[0011] 2) at least one silane coupling agent selected from amongcompounds represented by the following general formula (I) or (II):

[0012] wherein each of R represents an alkoxy or alkyl group having 1 to5 carbon atoms, the alkoxy or alkyl group having a chain in which atleast one ether bond may be contained, provided that at least two of theR are alkoxy groups, and

[0013] A represents an alkyl group having 1 to 10 carbon atoms, to whichat least one functional group selected from the group consisting of anamino group, a mercapto group, an epoxy group, a vinyl group, amethacryloxy group and halogens is bonded,

[0014] wherein each of R represents an alkoxy or alkyl group having 1 to5 carbon atoms, the alkoxy or alkyl group having a chain in which atleast one ether bond may be contained, provided that at least two of theR are alkoxy groups,

[0015] R₁ represents an alkylene group having 1 to 10 carbon atoms,optionally containing a sulfide group, an ether group or a nitrogen atombonded with a carbonyl group or sulfonyl group, the carbonyl or sulfonylgroup having a chain optionally containing R_(F) defined below,

[0016] B represents:

[0017] or a carbon to carbon bond directly bonding R₁ with R_(F), and

[0018] R_(F) is a perfluoroalkyl group having 1 to 10 carbon atoms;

[0019] 3) a crosslinking agent; and

[0020] 4) an inorganic filler.

[0021] It is preferred that the above crosslinking agent be a compoundrepresented by any one of the following general formulae (III) to (VI):

[0022] wherein Y represents an alkylidene group having 1 to 6 carbonatoms, a perfluoroalkylidene group having 1 to 10 carbon atoms, a groupof the formula —SO—, —O— or —C(═O)—, or a carbon to carbon bond directlybonding two benzene rings together, and X represents a hydroxyl group oran amino group;

[0023] wherein n is an integer of 1 to 10;

[0024] wherein R₂ represents H or NH₂, and n is an integer of 1 to 10;and

[0025] wherein R₃ represents OH or H. and R₄ represents H or NH₂.

[0026] The inorganic filler is preferably at least one member selectedfrom the group consisting of titanium dioxide, ferric oxide, zinc oxide,magnesium oxide, aluminum oxide, silicon dioxide, calcium silicate,aluminum silicate, magnesium silicate, barium sulfate, calcium sulfate,calcium carbonate, magnesium carbonate and barium carbonate.

DETAILED DESCRIPTION OF THE INVENTION

[0027] The fluoroelastomer composition of the present invention will bedescribed in detail below.

[0028] The fluoroelastomer composition comprises a fluoroelastomer, aspecified organosilicon compound, a crosslinking agent and an inorganicfiller.

[0029] The fluoroelastomer is a terpolymer of tetrafluoroethylene,either a perfluoro(alkyl vinyl ether) or a perfluoro(alkoxyalkyl vinylether) and a cyano group containing perfluorovinyl ether, provided thatthe alkyl or alkoxy of the perfluoro(alkyl vinyl ether) and perfluoro(alkoxyalkyl vinyl ether) has 1 to 5 carbon atoms. Preferred use is madeof those obtained by copolymerizing 50 to 75 mol %, especially 60 to 75mol %, of tetrafluoroethylene and 49.8 to 24.8 mol %, especially 39.8 to24.8 mol %, of either a perfluoro(alkyl vinyl ether) or aperfluoro(alkoxyalkyl vinyl ether) together with 0.2 to 5 mol %,especially 0.5 to 2 mol %, of a cyano group containing perfluorovinylether as a crosslinking moiety monomer.

[0030] Perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) orperfluoro(propyl vinyl ether) is preferably used as the perfluoro(alkylvinyl ether).

[0031] Perfluoro (methyl vinyl ether) is still preferably used as theperfluoro(alkyl vinyl ether).

[0032] As for the perfluoro (alkoxyalkyl vinyl ether), for example,

CF₂═CFOCF₂CF(CF₃)OC_(n)F_(2n+1)   (n:1-5)

CF₂═CFO(CF₂)₃OC_(n)F_(2n+1)   (n:1-5)

CF₂═CFOCF₂CF(CF₃)O(CF₂O)_(m)C_(n)F_(2n+1)   (n:1-5 and m:1-3)

[0033] or

CF₂═CFO(CF₂)₂OC_(n)F_(2n+1)   (n:1-5)

[0034] is used .

[0035] For example, the following compounds are used as the cyano groupcontaining perfluorovinyl ether:

CF₂═CFO(CF₂)_(n)OCF(CF₃)CN   (n: 2-4)

CF₂═CFO(CF₂)_(n)CN   (n: 2-12)

[0036] described in U.S. Pat. No. 3,546,186,

CF₂═CFO(CF₂CF(CF₃)O_(m)(CF₂)_(n)CN   (n:2 and m:1-5)

[0037] described in U.S. Pat. No. 4,138,426,

CF₂═CFO(CF₂CF(CF₂CF(CF₃)O)_(m)(CF₂)_(n)CN   (n: 1-4and m: 1-2)

[0038] described in U.S. Pat. No. 4,281,092, and

CF₂═CFO(CF₂CF(CF₃)O)_(n)CF₂CF(CF₃)CN   (n: 0-4)

[0039] described in U.S. Pat. Nos. 3,852,326 and 3,933,767.

[0040] As the silane coupling agent, there can be mentioned at least onesilane coupling agent selected from among compounds represented by thefollowing general formula (I) or (II):

[0041] wherein each of R represents an alkoxy or alkyl group having 1 to5 carbon atoms, the alkoxy or alkyl group having a chain in which atleast one ether bond may be contained, provided that at least two of theR are alkoxy groups, and

[0042] A represents an alkyl group having 1 to 10 carbon atoms, to whichat least one functional group selected from the group consisting of anamino group, a mercapto group, an epoxy group, a vinyl group, amethacryloxy group and halogens is bonded,

[0043] wherein each of R represents an alkoxy or alkyl group having 1 to5 carbon atoms, the alkoxy or alkyl group having a chain in which atleast one ether bond may be contained, provided that at least two of theR are alkoxy groups,

[0044] R₁ represents an alkylene group having 1 to 10 carbon atoms,optionally containing a sulfide group, an ether group or a nitrogen atombonded with a carbonyl group or sulfonyl group, the carbonyl or sulfonylgroup having a chain optionally containing R_(F) defined below,

[0045] B represents:

[0046] or a carbon to carbon bond directly bonding R₁ with R_(F), and

[0047] R_(F) is a perfluoroalkyl group having 1 to 10 carbon atoms.

[0048] Examples of the silane coupling agents include:

[0049] aminosilanes such as γ-aminopropyltrimethoxysilane,γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane,N-methyl-γ-aminopropyltrimethoxysilane,N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane,N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane and3-ureidopropyltrimethoxysilane;

[0050] mercaptosilanes such as γ-mercaptopropyltrimethoxysilane,γ-mercaptopropyltriethoxysilane andγ-mercaptopropylmethyldimethoxysilane;

[0051] vinylsilanes and methacryloxysilanes such asvinyltrimethoxysilane, vinyltriethoxysilane,vinyltris(β-methoxyethoxy)silane and γ-methacryloxytrimethoxysilane;

[0052] chlorosilanes such as γ-chloropropyltrimethoxysilane andγ-chloropropylmethyldimethoxysilane;

[0053] epoxysilanes such asβ-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane andγ-glycidoxypropylmethyldimethoxysilane; and

[0054] compounds of the formulae:

[0055] wherein n is 0-1, and R_(F) represents a perfluoroalkyl grouphaving 1 to 10 carbon atoms.

[0056] At compounding, when a direct compounding is performed, 0.2 to 3parts by weight, preferably 0.5 to 2 parts by weight, of silane couplingagent is used per 100 parts by weight of the above terpolymer.

[0057] Instead, the silane coupling agent may be incorporated bytreating the surface of an inorganic (inorg.) filler with the silanecoupling agent and compounding the treated inorganic filler with theabove terpolymer. In this method, the required amount (req. amt.) ofsilane coupling agent is calculated by the formula:

Req. amt. of silane coupling agent=[sp. surface area (m²/g) of inorg.filler×wt. (g) of inorg. filler]/(sp. surface area (m²/g) of silanecoupling agent]. (The term “sp.” represents “specific”. The term “wt.”represents “weight”).

[0058] However, when the above formula includes unknown parameter, thesilane coupling agent is used in an amount of 0.2 to 3 parts by weight,preferably 0.2 to 1 part by weight per inorganic filler.

[0059] The treatment of the inorganic filler with the silane couplingagent is most generally performed by the dry method, in which aseparately prepared aqueous solution of silane coupling agent orsolution of silane coupling agent in an organic solvent such as analcohol is added to the inorganic filler satisfactorily agitated in, forexample, Henschel mixer, and is uniformly dispersed and dried.

[0060] Alternatively, the treatment of the inorganic filler with thesilane coupling agent may be performed by the slurry method or the spraymethod.

[0061] The inorganic filler is preferably at least one member selectedfrom the group consisting of titanium dioxide, ferric oxide, zinc oxide,magnesium oxide, aluminum oxide, silicon dioxide, calcium silicate,aluminum silicate, magnesium silicate, barium sulfate, calcium sulfate,calcium carbonate, magnesium carbonate and barium carbonate.

[0062] The inorganic filler is compounded in an amount of 1 to 50 partsby weight, preferably 5 to 30 parts by weight, per 100 parts by weightof terpolymer.

[0063] The compound represented by the following general formula (III)or (IV) can be used as the crosslinking agent:

[0064] wherein Y represents an alkylidene group having 1 to 6 carbonatoms, a perfluoroalkylidene group having 1 to 10 carbon atoms, a groupof the formula —SO₂—, —O— or —C(═O)—, or a carbon to carbon bonddirectly bonding two benzene rings together, and X represents a hydroxylgroup or an amino group; and

[0065] wherein n is an integer of 1 to 10.

[0066] Further, the compound represented by the following generalformula (V) or (VI) can be used as the crosslinking agent:

[0067] wherein R₂ represents H or NH₂, and n is an integer of 1 to 10,

[0068] that is,

[0069] wherein n is an integer of 1 to 10; and

[0070] wherein R₃ represents OH or H, and R₄ represents H or NH₂,

[0071] preferably,

[0072] These crosslinking agents are used in an amount of 0.2 to 3 partsby weight, preferably 0.5 to 2 parts by weight, per 100 parts by weightof the above terpolymer.

[0073] The fluoroelastomer composition comprising the above componentsas essential ingredients can appropriately be loaded with a processingauxiliary, a plasticizer and other optionally needed compounding agents.

[0074] This composition can be prepared by compounding the compoundingagents by the use of, for example, a twin roll mill at 20 to 80° C.,preferably 30 to 60° C. The crosslinking of the composition is carriedout by heating at 150 to 250° C., preferably 170 to 220° C., for 5 to 60min, preferably 10 to 30 min, by means of, for example, a compressionmolding machine. For enhancing the properties of molded articles, it isgenerally preferred that the molding of the composition be subjected tooven vulcanization performed in air or an inert atmosphere at 150 to320° C., preferably 200 to 300° C., for about 10 to 50 hr.

EFFECT OF THE INVENTION

[0075] The present invention enables improving the moldability of thecyano group containing fluoroelastomer compounded with an inorganicfiller by virtue of the use of the silane coupling agent in combinationwith the crosslinking agent at the time of crosslinking thereof.

[0076] In particular, striking vulcanization accelerating effect isrecognized when the aminosilane is used as the silane coupling agent.The use of the aminosilane is thus suitable to the system compoundedwith a large amount of inorganic filler.

[0077] The color shading appearing on the surface of a molding afteroven vulcanization is obviated by the use of silane compound havingreducing activity, for example, the aminosilane, mercaptosilane orvinylsilane, as the silane coupling agent.

[0078] When use is made singly of the crosslinking agent of the generalformula (III), a molded article thus obtained exhibits strongly greenand color shading such as green streaks. By the combination of thecorsslinking agent with the silane coupling agent having reducingactivity, whole color of the article becomes ivory, and the colorshading is obviated.

[0079] The silane coupling agent compounded into the composition of thepresent invention also functions as an internal additive mold releaseagent to thereby improve the mold release properties of the compositionat the time of molding thereof.

EXAMPLE

[0080] The present invention will further be illustrated below withreference to the following Examples which in no way limit the scope ofthe invention.

[0081] Fluoroelastomer compositions were prepared from the followingcompounding agents by the use of the following method. Compounding agentfluoroelastomer (polymer ML₁₊₁₀ (150° C.): 63 pts) tetrafluoroethylene63.9 mol % perfluoro (methyl vinyl ether) 30.0 mol % perfluoro(2-cyano-3, 7-dioxa-8-nonene) 1.1 mol %.

[0082] This fluoroelastomer was produced by the method disclosed inJapanese Patent Laid-open Publication No. 8(1996)-120144.

[0083] crosslinking agent A

[0084] 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.

[0085] crosslinking agent B

[0086] 2,2,3,3,4,4,5,5-octafluorohexanediamidoxime.

[0087] wollastonite (1)

[0088] Nyad™400 produced by Nyco Minerals, Inc.

[0089] Wollastonite (2)

[0090] Nyad™G Wollastocoat produced by Nyco Minerals, Inc.

[0091] barium sulfate

[0092] BC produced by Sakai Chemical Industry Co., Ltd.

[0093] silicon dioxide (1)

[0094] Carplex™1120 produced by Shionogi & Co., Ltd.

[0095] silicon dioxide (2)

[0096] Aerosil™200 produced by Degussa.

[0097] titanium (IV) oxide

[0098] CR-93 produced by Ishihara Sangyo Kaisha, Ltd.

[0099] iron (III) oxide

[0100] Brown401 produced by Resinocolor Kogyo.

[0101] γ-aminopropyltrimethoxysilane

[0102] A-1100 produced by Nippon Unicar co., Ltd.

[0103] vinyltris(β-methoxyethoxy)silane

[0104] A-172 produced by Nippon Unicar Co., Ltd.

[0105] γ-mercaptopropyltrimethoxysilane

[0106] A-189 produced by Nippon Unicar Co., Ltd.

[0107]γ-perfluoro({1-(1-methyl-2-propoxy)ethoxy}propionyl)aminopropyltrimethoxysilaneA-1100(R_(F)).

[0108] This A-1110(R_(F)), ((CH₃O)₃Si(CH₂)₃NHCOCF(CF₃)OCF(CF₃)CF₂OCF₂CF₂CF₃), was synthesized from A-1100 and methylperfluoro-2,5-dimethyl-3,6-dioxanonanoate(MeOCOCF(CF₃)OCF(CF₃)CF₂OCF₂CF₂CF₃).

[0109] Moreover, in the present invention, the inorganic filler was dryblended with the above silane compound before being compounded into thecomposition.

[0110] Preparation of Composition

[0111] As specified in Tables 1 and 2, compounds were obtained byblending 100 parts by weight of perfluoropolymer with the crosslinkingagent optionally together with other compounding agents by means of atwin roll mill at 40 to 60° C.

[0112] The compounds thus obtaiend were compression molded for 15 mininto desired crosslinking products. The crosslinking temperature was220° C. in the use of crosslinking agent A and 190° C. in the use ofcrosslinking agent B.

[0113] These were further subjected to oven vulcanization performed in anitrogen atmosphere under the following temperature conditions.

[0114] The temperature was:

[0115] maintained at 90° C. for 4 hr,

[0116] raised to 204° C. over a period of 6 hr,

[0117] maintained at 204° C. for 18 hr,

[0118] raised to 288° C. over a period of 6 hr,

[0119] maintained at 288° C. for 18 hr, and

[0120] lowered to 100° C. over a period of 2 hr.

[0121] Method of Testing

[0122] The following tests were conducted to evaluate the properties ofthe obtained fluoroelastomer compositions.

[0123] Compound curing test

[0124] ODR (amplitude angle 1°) according to JIS K6300.

[0125] Testing of properties of curing products

[0126] tensile test according to DIN53504,

[0127] hardness according to DIN53505, and

[0128] compression set according to ASTM D395, Method B.

[0129] In Examples 13 and 14 and Comparative Example 5, furthermore, notonly the visual inspection of appearance of molded items but also thefollowing tests were performed:

[0130] In-air heat aging test

[0131] according to DIN53508, and

[0132] Oil resistance test

[0133] Immersion in specified oil was followed by measurements accordingto DIN53504 and DIN53505. TABLE 1 Example Example Example ExampleComposition 1 2 3 4 fluoroelastomer 100 100 100 100 curing agent A 1.41.4 1.4 1.4 barium sulfate 10 wollastonite (1) 10 wollastonite (2) 10silicon dioxide (1) silicon dioxide (2) 5 titanium (IV) oxide iron (III)oxide curing agent B γ-aminopropyltri- 1 1 1 methoxysilane vinyltris(β-methoxy- ethoxy) silane γ-mercaptopropyltri- methoxysilane ODR (24min) @/° C. 220 220 220 220 M_(L) kg-cm 32 32 32 32 M_(H) kg-cm 40 44 44(M_(H) ^(∞)) 49 (M_(H) ^(∞)) t_(s2) min 1.0 1.2 1.6 5.4 t_(c10) min 0.80.9 1.2 5.0 t_(c90) min 5.0 16.0 15.4 20.8 Mechanical properties M₁₀₀MPa 3.9 6.4 6.4 6.5 T_(b) MPa 13.7 17.0 18.3 17.9 E_(b) % 200 190 180190 hardness pts 70 72 73 70 Compression set % 250° C., 70 hr 33 32 3617 275° C., 70 hr 36 37 39 19 295° C., 70 hr 44 44 48 25 hot waterresistance test (200° C., 70 hr) hardness change (IRHD) pts −4 −1 0 −1volume increase % +3.4 +0.9 +2.4 +1.6 Example Example Example ExampleComposition 5 6 7 8 fluoroelastomer 100 100 100 100 curing agent A 1.41.4 1.4 barium sulfate wollastonite (1) wollastonite (2) 10 silicondioxide (1) silicon dioxide (2) titanium (IV) oxide 10 iron (III) oxide10 10 curing agent B 1 γ-aminopropyltri- 1 1 methoxysilane vinyltris(β-methoxy- 1 ethoxy) silane γ-mercaptopropyltri- methoxysilane ODR (24min) @/° C. 220 190 220 220 M_(L) kg-cm 32 30 24 19 M_(H) kg-cm 49(M_(H) ^(∞)) 38 (M_(H) ^(∞)) 39 (M_(H) ^(∞)) 38 (M_(H) ^(∞)) t_(s2) min1.2 8.5 6.4 6.2 t_(c10) min 1.1 7.2 7.4 5.8 t_(c90) min 14.0 18.5 21.221.2 Mechanical properties M₁₀₀ MPa 8.3 4.3 4.1 4.0 T_(b) MPa 18.6 19.320.7 21.4 E_(b) % 180 210 200 200 hardness pts 72 70 70 68 Compressionset % 250° C., 70 hr 37 29 21 — 275° C., 70 hr 37 31 28 295° C., 70 hr45 35 40 33 Hot water resistance test (200° C., 70 hr) hardness change(IRHD) pts −1 −2 −2 +2 volume increase % +1.6 +6.0 +2.8 +0.9 ExampleExample Example Example Composition 9 10 11 12 fluoroelastomer 100 100100 100 curing agent A 1.4 1.4 1.4 1.4 barium sulfate wollastonite (1)10 wollastonite (2) 10 silicon dioxide (1) silicon dioxide (2) 5titanium (IV) oxide 10 10 10 iron (III) oxide 10 curing agent Bγ-aminopropyltri- 1 methoxysilane vinyltris (β-methoxy- 1 ethoxy) silaneγ-mercaptopropyltri- 1 methoxysilane γ-perfluoro ({1- (1- 2 methyl-2-proxy) ethoxy}prop- ionyl) aminopropyl trimethoxysilane ODR (24 min) @/°C. 220 220 220 200 M_(L) kg-cm 23 21 20 24 M_(H) kg-cm 29 (M _(h) ^(∞))33 (M _(H) ^(∞)) 31 (M _(H) ^(∞)) 29 (M _(H) ^(∞)) t_(s2) min 5.2 9.88.4 10.2 t_(c10) min 7.8 4.8 6.8 6.0 t_(c90) min 17.8 22.3 22.0 18.3Mechanical properties M MPa 4.1 9.4 10.6 7.6 T_(b) MPa 17.8 17.0 20.818.4 E_(b) % 220 160 170 170 hardness pts 68 72 72 73 Compression set %250° C., 70 hr 35 21 22 27 275° C., 70 hr 40 23 23 30 295° C., 70 hr 4527 28 42 hot water resistance test (200° C., 70 hr) hardness change(IRHD) pts +1 −1 +1 −2 volume increase % +1.5 +3.2 +1.2 +3.0 Comp. Comp.Comp. Comp. Composition Ex. 1 Ex. 2 Ex. 3 Ex. 4 fluoroelastomer 100 100100 100 curing agent A 1.4 1.4 1.4 barium sulfate 10 wollastonite (1) 10wollastonite (2) silicon dioxide (1) 10 silicon dioxide (2) titanium(IV) oxide 10 iron (III) oxide curing agent B 1 γ-aminopropyltri-methoxysilane vinyltris (β-methoxy- ethoxy) silane γ-mercaptopropyltri-methoxysilane ODR (24 min) @/° C. 220 220 220 190 M_(L) kg-cm 22 26 a)26 M_(H) kg-cm 36 (M _(H) ^(∞)) 41 (M _(H) ^(∞)) 33 (M _(H) ^(∞)) t_(s2)min 7.4 3.4 8.1 t_(c10) min 7.4 3.0 6.0 t_(c90) min 21.2 20.0 11.5Mechanical properties M MPa b) b) b) 2.9 T_(b) MPa 13.3 E_(b) % 220hardness pts 67 Compression set % 250° C., 70 hr 35 275° C., 70 hr 34295° C., 70 hr 55 hot water resistance test (200° C., 70 hr) hardnesschange (IRHD) pts −2 volume increase % +4.4

[0134] TABLE 2 Composition Example 13 Example 14 Comp.Ex. 5fluoroelastomer 100 100 100 curing agent A 1.4 1.4 1.4 barium sulfate 1010 10 wollastonite (1) wollastonite (2) silicon dioxide (1) silicondioxide (2) titanium (IV) oxide 10 10 10 iron (III) oxide curing agent Bγ-aminopropyltri- methoxysilane vinyltris (β-methoxy- 1 ethoxy) silaneγ-mercaptopropyltri- 1 methoxysilane ODR (24 min) @/° C. 220 220 220M_(L) kg-cm 16 32 24 M_(H) kg-cm 36 (M _(H) ^(∞)) 24 (M _(H) ^(∞)) 31 (M_(H) ^(∞)) t_(s2) min 10.0 12.0 10.8 t_(c10) min 8.0 8.8 4.8 t_(c90) min22.1 22.4 22.4 Mechanical properties M MPa 5.1 5.3 6.0 T_(b) MPa 20.419.2 16.5 E_(b) % 200 190 190 hardness pts 70 71 71 Compression set %250° C., 70 hr 18 17 17 275° C., 70 hr 20 20 19 295° C., 70 hr 27 26 23hot water resistance test (200° C., 70 hr) hardness change (IRHD) pts +1−1 −3 volume increase % +1.0 +2.2 +3.0 Appearance of molding ivory ivoryblue uneven color In-air heat aging test (295° C., 70 hr) M₁₀₀ change %−17 −16 −18 T_(b) change % −7 −11 −12 E_(b) change % +15 +16 +16hardness change pts −1 −1 −3 weight change % −0.4 −0.4 −0.3 Oilresistance test ] BLEND ™770 (175° C., 70 hr) M₁₀₀ change % −8 −11 −14T_(b) change % −2 −6 −10 E_(b) change % +5 +5 +11 hardness change pts +2+1 +2 vol. increase % +0.9 +0.7 +0.6 SKYDROL ™LD-4 (125° C., 70 hr) M₁₀₀change % −24 −33 −27 T_(b) change % −16 −40 −21 E_(b) change % +5 −5 +16hardness change pts −1 −2 −2 vol. increase % +4.2 +4.9 +7.8

What is claimed is:
 1. A fluoroelastomer composition comprising: 1) afluoroelastomer consisting essentially of tetrafluoroethylene units,perfluoro(alkyl vinyl ether) units and cyano group containingperfluorovinyl ether units, provided that the alkyl of the perfluoro(alkyl vinyl ether) has 1 to 5 carbon atoms; 2) at least one silanecoupling agent selected from among compounds represented by thefollowing general formula (I) or (II):

wherein each of R represents an alkoxy or alkyl group having 1 to 5carbon atoms, said alkoxy or alkyl group having a chain in which atleast one ether bond may be contained, provided that at least two of theR are alkoxy groups, and A represents an alkyl group having 1 to 10carbon atoms, to which at least one functional group selected from thegroup consisting of an amino group, a mercapto group, an epoxy group, avinyl group, a methacryloxy group and halogens is bonded,

wherein each of R represents an alkoxy or alkyl group having 1 to 5carbon atoms, said alkoxy or alkyl group having a chain in which atleast one ether bond may be contained, provided that at least two of theR are alkoxy groups, R₁ represents an alkylene group having 1 to 10carbon atoms, optionally containing a sulfide group, an ether group or anitrogen atom bonded with a carbonyl group or sulfonyl group, saidcarbonyl or sulfonyl group having a chain optionally containing R_(F)defined below, B represents:

or a carbon to carbon bond directly bonding R₁ with R_(F), and R_(F) isa perfluoroalkyl group having 1 to 10 carbon atoms; 3) a crosslinkingagent; and 4) an inorganic filler.
 2. The fluoroelastomer composition asclaimed in claim 1, wherein the crosslinking agent is represented by thegeneral formula (III):

wherein Y represents an alkylidene group having 1 to 6 carbon atoms, aperfluoroalkylidene group having 1 to 10 carbon atoms, a group of theformula —SO₂—, —O— or —C(═O)—, or a carbon to carbon bond directlybonding two benzene rings together, and X represents a hydroxyl group oran amino group.
 3. The fluoroelastomer composition as claimed in claim1, wherein the crosslinking agent is represented by the general formula(IV):

wherein n is an integer of 1 to
 10. 4. The fluoroelastomer compositionas claimed in claim 1, wherein the crosslinking agent is represented bythe general formula (V):

wherein R₂ represents H or NH₂, and n is an integer of 1 to
 10. 5. Thefluoroelastomer composition as claimed in claim 1, wherein thecrosslinking agent is represented by the general formula (VI):

wherein R₃ represents OH or H, and R₄ represents H or NH₂.
 6. Thefluoroelastomer composition as claimed in claim 1, wherein the inorganicfiller is at least one member selected from the group consisting oftitanium dioxide, ferric oxide, zinc oxide, magnesium oxide, aluminumoxide, silicon dioxide, calcium silicate, aluminum silicate, magnesiumsilicate, barium sulfate, calcium sulfate, calcium carbonate, magnesiumcarbonate and barium carbonate.